Wire-unwinding devices are known from the state of the art. In particular, it is known for a wire drum, onto which wire is wound, to be rotatably supported so that the wire can be removed. It is necessary in a wire-unwinding device that the wire is unwound in a controlled manner. A predetermined wire tension must be assured in order to avoid loop formations or wire tears. The known wire-unwinding devices also have the disadvantage of not permitting large wire drums to be unwound in a reliable manner. Furthermore, known wire-unwinding devices do not guarantee that a change of the mechanical characteristics of the wire will be avoided.
A wire-unwinding machine is known from Swiss Patent No. 385 774, which is used to wind wires onto drums. This known device has a stationary guide roller or pulley rotatably supported on the housing. A guide pulley, which is changeable in position, is arranged in an area between the wire drum and the stationary guide pulley, with the wire being guided over the rollers in such a manner that its pregiven direction of curvature is maintained. Such a device is, however, not suited for use in spark eroding, electrical discharge machines for electric and also for driving reasons.
The basic purpose of the invention is to create a wireunwinding device for use with wire spark eroding, electrical discharge machines which, with a simple design and reliable operation, can also be equipped with very large wire drums and in which an influence of the mechanical characteristics or of the strength characteristics of the wire is avoided and which is suited for feeding the wire to the wire spark eroding machines in all occurring operating conditions.